lib: lutil matching without changing newlines

lib: lutil matching without changing newlines

Prior behavior of luCommand was to convert newlines to spaces in DUT
output before pattern matching. New method operating in parallel uses
re.DOTALL to mimic same behavior and allow preserving original DUT output.
The original output is needed for some scripts that parse line-by-line.

There is also some test code to compare match results using the
old way and new way and log a message if they are different. After
some short time we can develop confidence that using this new method
will not break any existing tests.

Signed-off-by: G. Paul Ziemba <paulz@labn.net>